Former Cabinet Minister Norman Tebbit has attacked plans for gay marriage, warning of the possibility of a lesbian queen and suggesting he could marry his own son to avoid tax.
In an outspoken interview, the Tory grandee told the Big Issue the government had "really fucked things up" by changing the law on marriage, and said it would drive voters into the arms of Ukip.
Tebbit's comments were made before Ukip gained more than 100 seats in the local elections.
"I said to a minister I know: have you thought this through? Because you're doing the law of succession, too," he told the magazine.
"When we have a queen who is a lesbian and she marries another lady and then decides she would like to have a child and someone donates sperm and she gives birth to a child, is that child heir to the throne?"
His concerns echoed those of Tory peer Lord True, who tried to change the Succession To The Crown Bill in March.
Tebbit, a former Tory Party chairman who served under Margaret Thatcher, also said the gay marriage change would allow parents to marry their children to get out of paying.
"It's like one of my colleagues said: we've got to make these same sex marriages available to all," he said.
"It would lift my worries about inheritance tax because maybe I'd be allowed to marry my son.
"Why not? Why shouldn't a mother marry her daughter? Why shouldn't two elderly sisters living together marry each other?"
He added: “I quite fancy my brother!”